Revisit the normal anatomy of the secondary pulmonary lobule Define the term bronchiolitis and recognize the imaging appearance at chest radiography and high resolution CT (HRCT) Describe the classification into either cellular or constrictive types and discuss the wide spectrum of causes Make an appropriate differential diagnosis and depict the mimics of small airways diseases

Small airways diseases, bronchiolitis, are very often found by radiologists and represent a true diagnostic challenge. It refers to bronchiolar inflammation and/or fibrosis. These bronchioles resemble branching linear structures that are connected to small centrilobular nodules, which results in the tree-in-bud pattern. HRCT plays an important role in detecting small airways diseases and is used in conjunction with clinical data and pathologic findings to solidify a diagnosis. It is able to detect both direct and indirect signs of bronchiolitis and therefore it will help the...

NORMAL ANATOMY The small airways, or bronchioles, are less than 2 mm internal diameter and lack cartilage. They are located at the center of the secondary pulmonary lobule which is the functional anatomic unit of the lungs, bounded by interlobular septa (Fig. 1). Terminal bronchiole is the last purely air conducting structure of the human respiratorysystem,eventually terminating in respiratory bronchioles, which are the longest bronchioles and supply alveoli and provide gas exchange. BRONCHIOLITIS AS A RADIOLOGIST CHALLENGE There are many diseases that cause bronchiolar inflammation...

Bronchiolitis is a very common finding at chest X-Ray and CT. That is why recognition of classic and additional imaging signs, along with clinical and history key elements, may be very useful to enable a focused diagnosis to guide the clinical management of patients.

Irene Vicente Zapata General University HospitalJosé María Morales Meseguer, University of Murcia,Department of Radiology, Spain Av marqués de los Vélez s/n E-30008, Murica (Spain) Phone: +34-696000026 e-mail :[email protected]

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